This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Dawes, S. S. Articles by Mizrahi, V. Search for Related Content PubMed PubMed Citation Articles by Dawes, S. S. Articles by Mizrahi, V.

 Previous Article  |  Next Article 

Infection and Immunity, November 2003, p. 6124-6131, Vol. 71, No. 11
0019-9567/03/$08.00+0     DOI: 10.1128/IAI.71.11.6124-6131.2003
Copyright © 2003, American Society for Microbiology. All Rights Reserved.

Ribonucleotide Reduction in Mycobacterium tuberculosis: Function and Expression of Genes Encoding Class Ib and Class II Ribonucleotide Reductases

Stephanie S. Dawes,¹ Digby F. Warner,¹ Liana Tsenova,^2, Juliano Timm,³ John D. McKinney,³ Gilla Kaplan,^2, Harvey Rubin,⁴ and Valerie Mizrahi^1*

MRC/NHLS/WITS Molecular Mycobacteriology Research Unit, School of Pathology of the National Health Laboratory Service and Department of Molecular Medicine and Hematology, University of the Witwatersrand Medical School, Johannesburg 2000, South Africa,¹ Laboratory of Cellular Physiology and Immunology,² Laboratory of Infection Biology, The Rockefeller University, New York, New York 10021,³ Division of Infectious Diseases, Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104⁴

Received 18 April 2003/ Returned for modification 1 July 2003/ Accepted 24 July 2003

Mycobacterium tuberculosis, the causative agent of tuberculosis, possesses a class Ib ribonucleotide reductase (RNR), encoded by the nrdE and nrdF2 genes, in addition to a putative class II RNR, encoded by nrdZ. In this study we probed the relative contributions of these RNRs to the growth and persistence of M. tuberculosis. We found that targeted knockout of the nrdF2 gene could be achieved only in the presence of a complementing allele, confirming that this gene is essential under normal, in vitro growth conditions. This observation also implied that the alternate class Ib small subunit encoded by the nrdF1 gene is unable to substitute for nrdF2 and that the class II RNR, NrdZ, cannot substitute for the class Ib enzyme, NrdEF2. Conversely, a nrdZ null mutant of M. tuberculosis was readily obtained by allelic exchange mutagenesis. Quantification of levels of nrdE, nrdF2, nrdF1, and nrdZ gene expression by real-time, quantitative reverse transcription-PCR with molecular beacons by using mRNA from aerobic and O₂-limited cultures showed that nrdZ was significantly induced under microaerophilic conditions, in contrast to the other genes, whose expression was reduced by O₂ restriction. However, survival of the nrdZ mutant strain was not impaired under hypoxic conditions in vitro. Moreover, the lungs of B6D2/F₁ mice infected with the nrdZ mutant had bacterial loads comparable to those of lungs infected with the parental wild-type strain, which argues against the hypothesis that nrdZ plays a significant role in the virulence of M. tuberculosis in this mouse model.

Editor: J. N. Weiser

Present address: Public Health Research Institute, International Center for Public Health, Newark, N.J.

This article has been cited by other articles:

• Roca, I., Torrents, E., Sahlin, M., Gibert, I., Sjoberg, B.-M. (2008). NrdI Essentiality for Class Ib Ribonucleotide Reduction in Streptococcus pyogenes. J. Bacteriol. 190: 4849-4858 [Abstract] [Full Text]  
• Boshoff, H. I. M., Xu, X., Tahlan, K., Dowd, C. S., Pethe, K., Camacho, L. R., Park, T.-H., Yun, C.-S., Schnappinger, D., Ehrt, S., Williams, K. J., Barry, C. E. III (2008). Biosynthesis and Recycling of Nicotinamide Cofactors in Mycobacterium tuberculosis: AN ESSENTIAL ROLE FOR NAD IN NONREPLICATING BACILLI. J. Biol. Chem. 283: 19329-19341 [Abstract] [Full Text]  
• Sinsimer, D., Huet, G., Manca, C., Tsenova, L., Koo, M.-S., Kurepina, N., Kana, B., Mathema, B., Marras, S. A. E., Kreiswirth, B. N., Guilhot, C., Kaplan, G. (2008). The Phenolic Glycolipid of Mycobacterium tuberculosis Differentially Modulates the Early Host Cytokine Response but Does Not in Itself Confer Hypervirulence. Infect. Immun. 76: 3027-3036 [Abstract] [Full Text]  
• Savvi, S., Warner, D. F., Kana, B. D., McKinney, J. D., Mizrahi, V., Dawes, S. S. (2008). Functional Characterization of a Vitamin B12-Dependent Methylmalonyl Pathway in Mycobacterium tuberculosis: Implications for Propionate Metabolism during Growth on Fatty Acids. J. Bacteriol. 190: 3886-3895 [Abstract] [Full Text]  
• Warner, D. F., Savvi, S., Mizrahi, V., Dawes, S. S. (2007). A Riboswitch Regulates Expression of the Coenzyme B12-Independent Methionine Synthase in Mycobacterium tuberculosis: Implications for Differential Methionine Synthase Function in Strains H37Rv and CDC1551. J. Bacteriol. 189: 3655-3659 [Abstract] [Full Text]  
• Torrents, E., Sahlin, M., Biglino, D., Graslund, A., Sjoberg, B.-M. (2005). Efficient growth inhibition of Bacillus anthracis by knocking out the ribonucleotide reductase tyrosyl radical. Proc. Natl. Acad. Sci. USA 102: 17946-17951 [Abstract] [Full Text]  
• Boshoff, H. I. M., Myers, T. G., Copp, B. R., McNeil, M. R., Wilson, M. A., Barry, C. E. III (2004). The Transcriptional Responses of Mycobacterium tuberculosis to Inhibitors of Metabolism: NOVEL INSIGHTS INTO DRUG MECHANISMS OF ACTION. J. Biol. Chem. 279: 40174-40184 [Abstract] [Full Text]  
• Timm, J., Post, F. A., Bekker, L.-G., Walther, G. B., Wainwright, H. C., Manganelli, R., Chan, W.-T., Tsenova, L., Gold, B., Smith, I., Kaplan, G., McKinney, J. D. (2003). Differential expression of iron-, carbon-, and oxygen-responsive mycobacterial genes in the lungs of chronically infected mice and tuberculosis patients. Proc. Natl. Acad. Sci. USA 100: 14321-14326 [Abstract] [Full Text]